中文说明：
考察一个长度为 的均直简支梁系统，梁的横截面积为A，弹性模量为E，质量密度为 ，在离简支梁左边支点的 距离和 距离处 施加动态载荷。
English Description：
A straight simply supported beam system with a length of is investigated. The cross-sectional area of the beam is a, the elastic modulus is e, and the mass density is. The dynamic load is applied at the distance and distance from the left fulcrum of the simply supported beam